1. Field of the Invention.
This invention directed to a sensing system, in general, and, in particular, to a sensing or detecting system which is used to detect toxic, hazardous or otherwise undesirable materials in a drainage system and to provide a suitable alarm signal when such materials are detected.
2. Prior Art.
One of the most visible problems of health and waste management techniques in this day and age is the impact of hazardous and/or toxic wastes and the disposal thereof. This disposal can be in accordance with accepted legal practices or not. Generally, legal disposal is monitored and kept within relatively safe parameters. Other disposals are not performed under controlled conditions. These uncontrolled disposals can be in the nature of overt or deliberate disposal such as dumping or the like. Conversely, uncontrolled disposals can be inadvertent disposals problems such as occur during involuntary spills, leakages, overflows or the like.
One of the areas of concern is the incursion of such wastes into drainage systems, whether deliberate or unintentional. This is especially a problem in those areas where the drainage system is permitted to empty, untreated into an adjacent body of water such as a lake, ocean, river, or the like. However, as environmentalists (among others) have determined, the continual dumping (deliberate or unintentional) of such wastes into such bodies of water is undesirable. These bodies of water become contaminated, the marine life suffers, tide pools are affected and the entire ecological system is eroded. Consequently, it is highly desirable to determine if and when certain wastes are found in the effluent being discharged by a drainage system.
It is equally desirable to determine when such wastes have accumulated to a substantial degree in storm drain systems. This can occur due to leakage, dumping, or merely as a result of certain wastes entering the drainage systems from streets during light rains, street cleaning, and so forth. That is, the wastes are washed from the surface streets into storm sewers and onward to the discharge location. While not necessarily so insidious, these wastes are just as damaging to the environment.
In a related environmental protection operation, a detection scheme is used in conjunction with detection of leaks from undergound tanks or the like. In this scheme, a hole is drilled into the ground adjacent to the underground tank, a vadous zone is created by inserting a suitable well liner, for example PVC pipe, into the hole, and a hydrocarbon detector is inserted therein. This detector can include a sensor probe which detects hydrocarbon, water and other elements.
In this system, if a leak occurs at the underground tank, the waste material seeps into the vadous zone and is detected by the sensor. However, this situation includes and comprises a known trouble spot (i.e. a buried tank) in a substantially fixed location wherein the vadous zone is relatively simple to produce.
In order to monitor drainage systems such as storm drains or the like, the water flow, the water depth, the drainage system and other variables must be considered while attempting to obtain a reliable, repeatable, detection operation. Consequently, the system of the instant invention is provided.